Ion Imprinting Research Articles

Preparation for nitrocellulose membrane-poly (vinyl alcohol)-ionic imprinting and its application to determine trace copper by room temperature phosphorimetry

Nitrocellulose membrane-poly (vinyl alcohol)-ionic imprinting (NCM-PVA-I-I) was prepared using Cu 2+ as template. The cavity in NCM-PVA-I-I matched Cu 2+ very well and the selectivity was high. Cu 2+ entered the cavity and then could form ionic association ([Cu 2+]·[(Fin −) 2]) with the anion of fluorescein (Fin −) outside the cavity by electrostatic effect. [Cu 2+]·[(Fin −) 2] could emit strong and stable room temperature phosphorescence on NCM-PVA-I-I. Its Δ I p was proportional to the content of Cu 2+. Based on the above facts, a new method for the determination of trace copper by solid substrate-room temperature phosphorimetry (NCM-PVA-I-I-SS-RTP, SS-RTP is the abbreviation of solid substrate-room temperature phosphorimetry) using NCM-PVA-I-I technique has been established. The linear range of this method was 2.00–144.00 fg Cu 2+ spot −1 (sample volume: 0.40 μL spot −1, corresponding concentration: 5.00–360.00 pg mL −1), and the detection limit calculated by 3Sb/ k was 0.43 fg Cu 2+ spot −1 (corresponding concentration: 1.1 × 10 −12 g mL −1, n = 11). Samples containing 2.00 and 144.00 fg Cu 2+spot −1 were measured, respectively, for seven times and R.S.D.s were 3.5% and 4.7%. NCM-PVA-I-I-SS-RTP could combine very well the characteristics of both the high sensitivity of SS-RTP and the high match and selectivity of NCM-PVA-I-I, and it was rapid, accurate, sensitive and with good repeatability. It has been successfully applied to determine trace copper in human hair and tea samples.

Investigation of the role of chelating ligand in the synthesis of ion-imprinted polymeric resins on the selective enrichment of uranium(VI)

Uranyl ion-imprinted polymeric (IIP) resins were prepared by dissolving stoichiometric amounts of uranyl nitrate and selected chelating ligands, viz. salicylaldoxime, catechol, succinicacid, 5,7-dichloroquinoline-8-ol and 4-vinyl pyridine in 2-methoxy ethanol (porogen) and copolymerizing thermally in the presence of 2-hydroxyethylmethacrylate (HEMA) and ethyleneglycol-dimethacrylate (EGDMA), using 2,2′-azobisisobutyronitrile (initiator). Again, IIP resins were also prepared on similar lines by utilizing ternary [uranium-non-vinylated ligand–vinylated ligand (4-vinyl pyridine)] complexes. Non-imprinted polymeric resins were identically prepared in both cases without the use of uranyl imprint ion. The percent enrichment and retention capacity studies showed significant imprinting effect in all cases. However, ion-imprinted polymeric resins formed with succinic acid (SA) or 5,7-dichloroquinoline-8-ol (DCQ) and 4-vinylpyridine (VP) alone gave quantitative enrichment and various parameters that influence the enrichment and elution were then optimized. The percent enrichment of uranium from synthetic seawater solutions was found to be 25.0 ± 0.5 and 83.0 ± 0.8 for SA–VP and DCQ–VP systems, respectively. The DCQ–VP-based IIP resins were successfully tested for the recovery of uranium from real seawater samples.

Novel surface ionic imprinting materials prepared via couple grafting of polymer and ionic imprinting on surfaces of silica gel particles

In this paper, a new surface molecular imprinting technique is put forward, and a kind of novel ion-imprinted polymers (IIPs) were prepared through a new approach: firstly functional macromolecule polyethyleneimine (PEI) was grafted onto the surfaces of silica gel particles via the coupling grafting method (“grafting to” method) and the composite material PEI/SiO2 with chemical linking was formed; secondly the ionic imprinting was carried out towards the macromolecule PEI grafted on the surface of silica particles using Cu2+ or Cd2+ ion as a template, epichlorohydrin (ECH) as a crosslinking agent and by coordination linkage actions, and Cu2+ ion (or Cd2+ ion)-imprinted material IIP-PEI/SiO2 was prepared. The binding characteristics of IIP-PEI/SiO2 for Cu2+ ion (or Cd2+ ion) were studied in detail by adopting both static and dynamic methods. The experimental results show that the ion-imprinting material IIP-PEI/SiO2 has specific recognition ability for the template ions, and this character displays mainly in two aspects: (1) it has high affinity for the template ions, its binding amounts for the template ions are much greater than that of the non-imprinted composite material PEI/SiO2, and the adsorption capacity enhances nearly two times compared to PEI/SiO2; (2) it has excellent selectivity for the template ions, for the IIP-PEI/SiO2 by using Cu2+ as template ion, its selectivity coefficients relative to Zn2+ and Ni2+ are 80.21 and 86.08, respectively, and for the IIP-PEI/SiO2 by using Cd2+ as template ion, its selectivity coefficients relative to Cr3+ and Pb2+ are 77.05 and 88.22, respectively. Besides, the imprinting material IIP-PEI/SiO2 has a fine elution property using HCl solution as eluent. The obtained imprinting material by using the new surface molecular imprinting techniques possesses superexcellent binding property for template molecules or ions because of the distribution of imprinted cavities in a thin polymer layer and smaller diffusion barrier.

Ion imprinted polymer particles for separation of yttrium from selected lanthanides

Lanthanide(III) (Dy, Gd, Tb and Y) ion imprinted polymer (IIP) materials were synthesized via single pot reaction by mixing lanthanide imprint ion with 5,7-dichloroquinoline-8-ol, 4-vinylpyridine, styrene, divinylbenzene and 2,2'-azobisisobutyronitrile in 2-methoxyethanol porogen. The imprint ion was removed by stirring the above materials (after powdering) with 6 mol/L HCl to obtain the respective lanthanide IIP particles. Y-Dy, Y-Gd and Dy-Gd polymer particles were obtained by physically mixing equal amounts of the respective leached individual lanthanide(III) particles. Control polymer (CP) particles were similarly prepared without imprint ion. Application of the above synthesized polymer particles was tested for separation of Y from Dy, Gd and Tb employing batch and column SPE methods using inductively coupled plasma atomic emission spectrometry for the determination. Optimization studies show that Y present in 500 mL can be preconcentrated using Dy-Gd IIP particles and eluted with 20 mL of 1.0 mol/L of HCl, providing an enrichment factor of approximately 25. Dy-Gd IIP particles offer higher selectivity coefficients for Y over other lanthanides compared to other IIP particles and commercial liquid-liquid extractants. Selectivity studies for Y over other coexisting inorganic species (other than lanthanides) were also conducted and the results obtained show a quantitative separation of Y from other inorganics other than Cu(II) and Fe(III). Furthermore, both batch and column studies indicate the purification of yttrium concentrate from 55.0 +/- 0.2 to 65.2 +/- 0.2% in a single stage of operation.

Removal of Toxic Uranium from Synthetic Nuclear Power Reactor Effluents Using Uranyl Ion Imprinted Polymer Particles

Major quantities of uranium find use as nuclear fuel in nuclear power reactors. In view of the extreme toxicity of uranium and consequent stringent limits fixed by WHO and various national governments, it is essential to remove uranium from nuclear power reactor effluents before discharge into environment. Ion imprinted polymer (IIP) materials have traditionally been used for the recovery of uranium from dilute aqueous solutions prior to detection or from seawater. We now describe the use of IIP materials for selective removal of uranium from a typical synthetic nuclear power reactor effluent. The IIP materials were prepared for uranyl ion (imprint ion) by forming binary salicylaldoxime (SALO) or 4-vinylpyridine (VP) or ternary SALO-VP complexes in 2-methoxyethanol (porogen) and copolymerizing in the presence of styrene (monomer), divinylbenzene (cross-linking monomer), and 2,2'-azobisisobutyronitrile (initiator). The resulting materials were then ground and sieved to obtain unleached polymer particles. Leached IIP particles were obtained by leaching the imprint ions with 6.0 M HCl. Control polymer particles were also prepared analogously without the imprint ion. The IIP particles obtained with ternary complex alone gave quantitative removal of uranyl ion in the pH range 3.5-5.0 with as low as 0.08 g. The retention capacity of uranyl IIP particles was found to be 98.50 mg/g of polymer. The present study successfully demonstrates the feasibility of removing uranyl ions selectively in the range 5 microg - 300 mg present in 500 mL of synthetic nuclear power reactor effluent containing a host of other inorganic species.

Selective Solid-Phase Extraction of Trace Copper Ions in Aqueous Solution with a Cu(II)-Imprinted Interpenetrating Polymer Network Gel Prepared by Ionic Imprinted Polymer (IIP) Technique

An Cu(II)-imprinted interpenetrating polymer network (IPN) gel of epoxy-diethylenetriamine and methacrylic acid-acrylamide-N,N′-methylene-bis-(acrylamide) was synthesized by the ionic imprint polymer (IIP) technique. The first polymer network is formed by epoxy gelation with diethylenetriamine. The other is formed by copper methacrylate co- polymerization with acrylamide and cross-linker N,N′-methylene-bis-(acrylamide). The adsorption–desorption characteristics of the IPN gel as a highly selective solid-phase extraction (SPE) and preconcentration adsorbent for Cu2+ from aqueous solution were investigated. The experimental results show that trace Cu2+ ions can be quantitatively enriched at pH 5 with recovery >95%. The maximum static adsorption capacity of the ion-imprinted functionalized gel adsorbent was 76 mg g−1. Comparing with non-imprinted IPN gel, the imprinted IPN gel has higher adsorption capacity and selectivity for Cu2+ by the static adsorption–desorption experiment. Simultaneously, the times of adsorption equilibration and complete desorption were remarkably short. The precision (RSD) for 11 replicate adsorbent extractions of 20 ng mL−1 Cu2+ was 3.4%. The established procedure was applied to two real water samples with satisfactory results. The prepared ion-imprinted IPN gel adsorbent was shown to be promising for solid-phase extraction coupled with atomic absorption spectrometry (AAS) for the determination of trace copper in real samples. In addition, the coordination interaction of Cu2+ and functional groups of the IPN gel adsorbent was primarily discussed by FT-IR spectra.

Ion Imprinted Polymer Solid Phase Extraction (IIP‐SPE) for Preconcentrative Separation of Erbium(III) From Adjacent Lanthanides and Yttrium

Abstract Erbium(III) ion imprinted polymer (IIP) materials were prepared by photochemical polymerization of the ternary complex, Erbium(III)—5,7‐dichloroquinoline‐8‐ol‐4‐vinylpyridine, with methyl methacrylate (functional monomer) and ethylene glycol dimethacrylate (crosslinking monomer) in the presence of 2,2′‐azobisisobutyronitrile (initiator). The synthesis was carried out in 2‐methoxy ethanol (porogen) medium and the resultant material was filtered, dried and powdered to form unleached polymer particles. The imprint ion (erbium(III)) was removed by stirring the above particles with 6 mol/l HCl to obtain leached polymer particles. These leached particles are termed erbium(III) ion imprinted polymer (IIP) particles as it selectively rebind erbium(III) ions. Non‐imprinted/control polymer (CP) particles were similarly prepared without the imprint ion. CP and unleached and leached IIP particles were characterized by XRD, microanalysis, and UV‐visible spectrophotometric studies. Various parameters that infl...

Synthesis, characterization, and analytical applications of erbium(III) ion imprinted polymer particles prepared via γ-irradiation with different functional and crosslinking monomers

Erbium(III) ion imprinted polymer (IIP) particles were synthesized by preparing erbium(III)–5,7-dichloroquinoline-8-ol–4-vinylpyridine prepolymer complex and then copolymerizing via γ-irradiation with different functional and crosslinking monomer combinations, viz. styrene–divinyl benzene, 2-hydroxyethyl methacrylate (HEMA)–ethylene glycoldimethacrylate (EGDMA), methyl methacrylate (MMA)–EGDMA. The erbium(III) imprint ion was removed by stirring the above particles with 6.0 mol l −1 HCl to obtain leached IIP particles. Control polymer (CP) particles were prepared without imprint ion. Again, CP, unleached and leached IIP particles were characterized by XRD, UV–vis spectrophotometric, pore size, SEM, and swelling ratio studies. The preconcentration of traces of erbium(III) during rebinding with leached IIP particles was studied as a function of pH, weight of polymer material, preconcentration and elution times, eluent concentration and volume, and aqueous phase volume. These studies indicate that as low as 2 μg of erbium(III) present in 500 ml can be preconcentrated into 20 ml of 1.0 mol l −1 HCl, and thus providing an enrichment factor of ∼25. Furthermore, the present study indicates that styrene–divinyl benzene-based IIP could be a better choice for the separation of erbium(III) from yttrium(III), dysprosium(III), holmium(III), and thulium(III) compared to HEMA–EGDMA and MMA–EGDMA-based IIPs.

Investigation of different polymerization methods on the analytical performance of palladium(II) ion imprinted polymer materials

Palladium(II) ion imprinted polymer (IIP) materials were prepared via bulk, precipitation and suspension polymerization methods using similar compositions. In these polymerization methods, the polymerization mixture consists of a ternary complex of palladium(II) imprint ion with 8-aminoquinoline (AQ), 4-vinyl pyridine (VP, monomer), 2-hydroxyethyl methacrylate (HEMA, functional monomer), ethylene glycoldimethacrylate (EGDMA, cross-linking monomer), 2,2′-azobisisobutyronitrile (AIBN, initiator) and 2-methoxy ethanol (Porogen). Various polymerization methods were carried out by thermal means and IIP materials thus obtained were leached with 50% (v/v) HCl to obtain leached IIP particles. Control polymer (CP) particles were similarly prepared by all the three polymerization methods. The above synthesized polymer particles were characterized physically and morphologically by using FTIR, TGA, CHN, X-ray diffraction (XRD) and scanning electron microscopic (SEM) techniques. Furthermore, their capacity to rebind palladium(II) was investigated from dilute aqueous solutions and in presence of selected precious and transition elements (which are known to coexist with palladium in its mineral deposits). The rebinding studies of IIP particles obtained via bulk, precipitation and suspension methods reveal that (i) percent enrichment is quantitative with bulk and precipitation, and ∼72% only in case of suspension; (ii) retention capacities are 28.82, 20.16 and 18.76 mg palladium(II)/g materials, respectively; (iii) selectivity for palladium(II) over other noble and transition elements lies in the order bulk ∼ precipitation > emulsion. Moreover, the IIP particles obtained by all three polymerization methods exhibit imprinting effect when compared with respective CP particles.

Selective recognition of neodymium (III) using ion imprinted polymer particles.

Neodymium (III) ion-imprinted polymer (IIP) materials were prepared by the copolymerization of neodymium (III)-5,7-dichloroquinoline-8-ol-4-vinylpyridine ternary complex with styrene(monomer), divinyl benzene (crosslinking monomer) in the presence of 2,2'-azobisisobutyronitrile (initiator). The synthesis was carried out in 2-methoxy ethanol medium (porogen) and the resultant material was filtered, washed, dried and powdered to form unleached IIP particles. The imprint ion was removed by stirring the above particles with 50% (v/v) HCl for 6 h to obtain leached IIP particles with cavities in the polymer particles. Control polymer (CP) particles were similarly prepared without imprint ion, i.e. neodymium (III). CP, unleached and leached IIP particles were characterized by TLC, IR, microanalysis, XRD and UV-visible spectrophotometric studies. The preconcentration of 5-150 microg of neodymium (III) ions present in 500 ml of solution was possible with as little as 40 mg of neodymium (III) IIP particles in the pH range 7.5-8.0 with a detection limit of 50 ng/l. Five replicate determinations of 25 microg of neodymium (III) present in 500 ml of solution gave a mean absorbance of 0.120 with a relative standard deviation of 2.65%. The imprinting effect of IIP particles was noticed in all preconcentration and selectivity studies when compared with CP particles. Furthermore, the selectivity coefficients of neodymium (III) IIP particles were much higher compared with the reported separation factors for the best liquid-liquid extractants, viz. di-2-ethylhexyl phosphoric acid and 2-ethylhexyl-ethylhexyl phosphonate. Kinetic and isotherm studies during rebinding of neodymium (III) onto IIP particles were also carried out.

Preconcentrative separation of erbium from Y, Dy, Ho, Tb and Tm by using ion imprinted polymer particles via solid phase extraction

Erbium(III) ion imprinted polymer particles were synthesized by preparing ternary complex of erbium imprint ion with 5,7-dichloroquinoline-8-ol (DCQ) and 4-vinylpyridine (VP) and then thermally copolymerizing with methyl methacrylate (functional monomer) and ethylene glycol dimethacrylate (cross linking monomer) in the presence of 2-methoxy ethanol (porogen) and 2,2′-azobisisobutyronitrile (initiator). The imprint ion was removed by stirring the above particles with 50% (v/v) HCl to obtain leached IIP particles. Control polymer (CP) particles were similarly prepared without imprint ion. CP and unleached and leached IIP particles were characterized by spectral, thermal, microanalysis and nitrogen adsorption studies. The preconcentration and selectivity studies for erbium and other selected lanthanides were carried out with leached CP and IIP particles. The preconcentration of 2.0–250 μg of erbium(III) present in 250 ml of solution was possible with as low as 50 mg of IIP particles in the pH range 7.3–7.8. Seven replicate determinations of 25 μg of erbium(III) present in 250 ml of solution gave a mean absorbance of 0.148 with a relative standard deviation of 2.5%. The detection limit corresponding to three times the standard deviation of the blank was found to be 2 μg/250 ml.

Determination of heavy metal ions in mixed solution by imprinted SAMs

Specific selectivity toward different heavy metal ions could be introduced into self-assembled monolayers (SAMs) by ion imprinting. In the mixed solution, good response toward mercury ions could be obtained on mercury ions imprinted SAMs, the copper ions imprinted SAMs presented good selectivity toward copper ions, while on lead ions imprinted SAMs, significantly higher insertion of lead ions than mercury and copper ions were observed. Linear calibration plots were obtained for each heavy metal ion and the regression equations were: I p /(10 −6 A)=−1.721+(−4.210) [Hg(II)]/(10 −6 M), I p /(10 −6 A)=−1.438+(−1.420) [Cu(II)]/(10 −6 M) and I p /(10 −6 A)=−3.779+(−3.551) [Pb(II)]/(10 −6 M) for mercury, copper and lead ions, respectively. The detection limits were determined to be: 1.46×10 −8 M for Hg(II), 3.73×10 −8 M for Cu(II) and 4.34×10 −8 M Pb(II). The decreases in current response for mercury, copper and lead ions in the presence of 100-fold interferential ions were: 3.37%, 9.16% and 7.60%, respectively. Acceptable recoveries were obtained in mixed solutions at both high and low concentrations.

Influence of binary/ternary complex of imprint ion on the preconcentration of uranium(VI) using ion imprinted polymer materials

Ion imprinted polymer (IIP) materials were prepared for uranyl ion (imprint ion) by forming binary (5,7-dichloroquinoline-8-ol (DCQ) or 4-vinylpyridine (VP)) or ternary (5,7-dichloroquinoline-8-ol and 4-vinylpyridine) complexes in 2-methoxy ethanol (porogen) and copolymerizing in the presence of styrene and divinyl benzene as functional and crosslinking monomers, respectively and 2,2′-azobisisobutyronitrile as initiator. IIP particles were obtained by leaching the imprint ion in these polymer materials with 50% (v/v) hydrochloric acid, filtering, drying in an oven at 50 °C and grinding. Control polymer particles were also prepared under identical conditions. The above synthesized polymer particles were characterized by IR, CHN, X-ray diffraction, and pore size analyses. These leached polymer particles can now pick up uranyl ions from dilute aqueous solutions. The IIP particles obtained with ternary complex of uranyl ion alone gave quantitative enrichment of traces of uranyl ions from dilute aqueous solutions. The optimal pH for quantitative enrichment is 4.5–7.5 and eluted completely with 10 ml of 1.0 M HCl. The retention capacity of uranyl IIP particles was found to be 34.05 mg of uranyl ion per gram of polymer. Further, the percent extraction, distribution ratio, and selectivity coefficients of uranium and other selected inorganic ions were also evaluated. Five replicate determinations of 25 μg of uranium present in 1.0 l of aqueous solution gave a mean absorbance of 0.036 with a relative standard deviation of 2.50%. The detection limit corresponding to three times the standard deviation of the blank was found to be 5 μg l −1.

Synthesis of imprinted polymer material with palladium ion nanopores and its analytical application

Ion imprinted polymer (IIP) materials with nanopores were prepared by formation of ternary complex of palladium imprint ion with dimethylglyoxime (DMG) and 4-vinylpyridine (VP, functional monomer) and thermally copolymerizing with styrene (crosslinking monomer) and divinylbenzene (cross linker) and 2,2′-azobisisobutyronitrile as initiator. The synthesis was carried out with cyclohexanol as porogen and subsequently leached with 50% (v/v) HCl to obtain leached IIP particles. These leached IIP particles can now pick up palladium ions from dilute aqueous solutions. The optimal acidity for quantitative enrichment was 0.2–0.4N HCl and eluted completely by stirring for 15 min with 2×10 ml of 50% (v/v) HCl. The palladium ion imprinting polymer gave 100 times higher distribution ratio than ion recognition (blank) polymer (IRP). Further, percent extraction, distribution ratio and selectivity coefficients of palladium and other selected inorganic ions using IRP and IIP particles were determined and compared. Five replicate determinations of 50 μg of palladium in 1 l of solution gave a mean absorbance of 0.200 with a relative standard deviation of 2.12%. The detection limit corresponding to three times the standard deviation of the blank was 2.5 μg of palladium/l.

Synthesis and Analytical Applications of Uranyl Ion Imprinted Polymer Particles

Uranyl ion imprinted polymer particles were prepared by the copolymerization of styrene monomer and a crosslinking agent divinyl benzene in the presence of -5,7-dichloroquinoline-8-ol-4-vinyl pyridine ternary complex as template where in is the imprint ion in presence of 2,2′-azo-bis-isobutyronitrile as initiator. The Uranyl ion was removed from the polymer particles by leaching with 1:1 HCl, which leaves cavities in the polymer particles. The leached polymer particles preconcentrate ion from dilute aqueous and synthetic seawater solutions. Further, these particles find use in the separation of ion from various bivalent, trivalent, and tetravalent, inorganic ions. The accuracy of the developed enrichment procedure was tested by analyzing marine sediment certified reference material supplied by National Research Council (NRC), Canada. Further, the developed procedure has been successfully employed to analyze real soil and sediment samples.

Ion imprinted polymer particles: synthesis, characterization and dysprosium ion uptake properties suitable for analytical applications

Dysprosium(III) ion imprinted polymer particles were prepared by the copolymerization of styrene monomers and a crosslinking agent divinylbenzene in the presence of dysprosium(III)–5,7-dichloroquinoline-8-ol–4-vinyl pyridine ternary complex wherein dysprosium(III) ion is the imprint ion and is used to form the imprinted polymer. The dysprosium(III) ion was removed from polymer particles by leaching with 1:1 HCl which leaves a cavity in the polymer particles. The polymer particles both prior to and after leaching have been characterized by IR, TGA, DTA and XRD studies. The leached particles selectively preconcentrated dysprosium ion from dilute aqueous solutions as determined spectrophotometrically using Arsenazo-I as reagent. The optimum pH value for quantitative enrichment is 6–9 and desorption can be achieved by using 25 ml of 1 mol/l of HCl. The retention capacity of the polymer particles was found to be 40.15 mg/g, which is much higher than MIPs prepared by other imprinting techniques. The dysprosium ion imprinting polymer gave 40 times higher distribution ratio for dysprosium ion compared to blank polymer. More significantly the selectivity coefficients of dysprosium compared to other lanthanides results in enhancement by 60–180-fold. The separation factors with respect to other selected lanthanides were also compared with liquid–liquid extractive separation using di-2-ethylhexyl phosphoric acid (D2EHPA) as extractant. The selectivity of dysprosium ion imprinting polymer (IIP) particles for dysprosium over yttrium is much higher and comparable in case of Nd and Lu when compared to conventional extractant such as D2EHPA in liquid–liquid extraction (LLE). Five replicate determinations of 50 μg of dysprosium present in 250 ml of sample gave a mean absorbance of 0.150 with a relative standard deviation of 2.42%. The detection limit corresponding to three times the standard deviation of the blank was found to be 2 μg/250 ml.

MARKET REPORT: Membrane Separation

In order to effectively extract lithium from salt lake brine, a novel magnetic graphene oxide-based lithium ion-imprinted polymer (IIP-GO/Fe3O4@C) was developed by combining magnetic separation technology with surface ion imprinting technology. GO/Fe3O4@C, which is composed of graphene oxide (GO) and Fe3O4@C, was modified by silane coupling agent KH570 and then grafted with methacrylic acid (MAA). The IIP-GO/Fe3O4@C achieved excellent Li+ separation performance, including an adsorption capacity of 31.24 mg/g, good regeneration performance (91% of the initial value after six adsorption–desorption cycles), a moderate equilibrium time of about 2 h, and relatively high selectivity against Na+, K+, and Mg2+ of 14.31, 12.05, and 10.9, respectively. These excellent properties are due to the synergistic effect between the construction of adsorption sites brought by the high specific surface area (225.8 m2/g) of GO/Fe3O4@C skeleton and the particular recognition of Li+ by 2-hydroxymethyl-12-crown ether-4. Therefore, IIP-GO/Fe3O4@C can be used as a prominent candidate for extracting lithium from salt lake brine.

Ionic imprinted resins based on EDTA and DTPA derivatives for lanthanides(III) separation

Ionic imprinting resins bearing polycarboxylic acids groups were studied in lanthanides(III) separation. Two monomers, diethylenetriamine pentaacetic acid (DTPA) and ethylenediaminetetraacetic acid (EDTA) derivatives, were synthesised and then polymerised in alcoholic medium using a free radical source. Solid–liquid competitive extraction was carried out using an aqueous solution containing gadolinium(III) and lanthanum(III) cations. Crosslinking ratios, conditioning of resins and type of chelating monomers were studied. Best results were obtained when polymers based on DTPA derivative were converted to H + form.

Ionic imprinting effect in gadolinium/lanthanum separation

A new method based on the use of cation imprinted polymers to separate lanthanum and gadolinium cations is proposed. Using a styrene-DTPA monomer specific of one of these elements, an improvement in separation selectivity is observed when a tailor-made gadolinium imprinted polymer is compared to a non-imprinted or blank polymer.

Incorporation of nano-particle sites in polymer matrix by Metal ion imprinting

ABSTRACTWe present an approach for synthesizing polymer matrices that have been pre-organized to bind metal ions selectively. The acyclic chelator, triethylenetetramine, was modified to include a polymerizable functional group and then complexed with a target metal ion. Unlike macro cyclic ligands, the acyclic chelators have the flexibility to form chelation rings that are dependent on metal-ion size and geometry. Therefore, we have used the complexation step as a means to optimize the chelator conformation for a particular metal ion. The resulting complex was then cross linked with the matrix monomer, TRIM (2-ethyl-2-(hydroxymethyl)propane-1,3-diol trimethacrylate), to provide a rigid polymer matrix for stabilization of the conformation for the metal-ligand site. These sites were then tested for selectivity towards the imprinted metal ion. Unlike imprinting for larger molecules, the relatively smaller size of the metal ions facilitated their access to the imprinted sites embedded in the porous polymers. In addition to metal-binding applications, polymeric materials doped with metal nanoparticles and metal ions can exhibit interesting physical, chemical, optical and electronic properties.